WCDH: introduce BARE_FEATURES

This allows defining compat versions of some C/C++ features with the name of the
keyword itself, so all code can look as if it was written for the new language
standard.
This commit is contained in:
Rolf Eike Beer 2018-03-19 21:42:25 +01:00
parent 561238bb6f
commit f38d050231
5 changed files with 127 additions and 34 deletions

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@ -0,0 +1,6 @@
wcdh-raw-features
-----------------
* The :module:`WriteCompilerDetectionHeader` module now supports the
``BARE_FEATURES`` argument which allows to add a compatibility define for
the exact keyword of a new language feature.

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@ -17,6 +17,7 @@
# [OUTPUT_FILES_VAR <output_files_var> OUTPUT_DIR <output_dir>]
# COMPILERS <compiler> [...]
# FEATURES <feature> [...]
# [BARE_FEATURES <feature> [...]]
# [VERSION <version>]
# [PROLOG <prolog>]
# [EPILOG <epilog>]
@ -83,10 +84,14 @@
# See the :manual:`cmake-compile-features(7)` manual for information on
# compile features.
#
# ``BARE_FEATURES`` will define the compatibility macros with the name used in
# newer versions of the language standard, so the code can use the new feature
# name unconditionally.
#
# ``ALLOW_UNKNOWN_COMPILERS`` and ``ALLOW_UNKNOWN_COMPILER_VERSIONS`` cause
# the module to generate conditions that treat unknown compilers as simply
# lacking all features. Without these options the default behavior is to
# generate a ``#error`` for unknown compilers.
# generate a ``#error`` for unknown compilers and versions.
#
# Feature Test Macros
# ===================
@ -148,20 +153,24 @@
# ``ClimbingStats_CONSTEXPR`` macro will expand to ``constexpr``
# if ``cxx_constexpr`` is supported.
#
# The following features generate corresponding symbol defines:
# If ``BARE_FEATURES cxx_final`` was given as argument the ``final`` keyword
# will be defined for old compilers, too.
#
# ========================== =================================== =================
# Feature Define Symbol
# ========================== =================================== =================
# ``c_restrict`` ``<PREFIX>_RESTRICT`` ``restrict``
# ``cxx_constexpr`` ``<PREFIX>_CONSTEXPR`` ``constexpr``
# The following features generate corresponding symbol defines and if they
# are available as ``BARE_FEATURES``:
#
# ========================== =================================== ================= ======
# Feature Define Symbol bare
# ========================== =================================== ================= ======
# ``c_restrict`` ``<PREFIX>_RESTRICT`` ``restrict`` yes
# ``cxx_constexpr`` ``<PREFIX>_CONSTEXPR`` ``constexpr`` yes
# ``cxx_deleted_functions`` ``<PREFIX>_DELETED_FUNCTION`` ``= delete``
# ``cxx_extern_templates`` ``<PREFIX>_EXTERN_TEMPLATE`` ``extern``
# ``cxx_final`` ``<PREFIX>_FINAL`` ``final``
# ``cxx_noexcept`` ``<PREFIX>_NOEXCEPT`` ``noexcept``
# ``cxx_final`` ``<PREFIX>_FINAL`` ``final`` yes
# ``cxx_noexcept`` ``<PREFIX>_NOEXCEPT`` ``noexcept`` yes
# ``cxx_noexcept`` ``<PREFIX>_NOEXCEPT_EXPR(X)`` ``noexcept(X)``
# ``cxx_override`` ``<PREFIX>_OVERRIDE`` ``override``
# ========================== =================================== =================
# ``cxx_override`` ``<PREFIX>_OVERRIDE`` ``override`` yes
# ========================== =================================== ================= ======
#
# Compatibility Implementation Macros
# ===================================
@ -195,18 +204,18 @@
# decorator or a compiler-specific decorator such as ``__alignof__``
# used by GNU compilers.
#
# ============================= ================================ =====================
# Feature Define Symbol
# ============================= ================================ =====================
# ============================= ================================ ===================== ======
# Feature Define Symbol bare
# ============================= ================================ ===================== ======
# ``cxx_alignas`` ``<PREFIX>_ALIGNAS`` ``alignas``
# ``cxx_alignof`` ``<PREFIX>_ALIGNOF`` ``alignof``
# ``cxx_nullptr`` ``<PREFIX>_NULLPTR`` ``nullptr``
# ``cxx_nullptr`` ``<PREFIX>_NULLPTR`` ``nullptr`` yes
# ``cxx_static_assert`` ``<PREFIX>_STATIC_ASSERT`` ``static_assert``
# ``cxx_static_assert`` ``<PREFIX>_STATIC_ASSERT_MSG`` ``static_assert``
# ``cxx_attribute_deprecated`` ``<PREFIX>_DEPRECATED`` ``[[deprecated]]``
# ``cxx_attribute_deprecated`` ``<PREFIX>_DEPRECATED_MSG`` ``[[deprecated]]``
# ``cxx_thread_local`` ``<PREFIX>_THREAD_LOCAL`` ``thread_local``
# ============================= ================================ =====================
# ============================= ================================ ===================== ======
#
# A use-case which arises with such deprecation macros is the deprecation
# of an entire library. In that case, all public API in the library may
@ -252,6 +261,37 @@ macro(_simpledefine FEATURE_NAME FEATURE_TESTNAME FEATURE_STRING FEATURE_DEFAULT
endif()
endmacro()
macro(_simplebaredefine FEATURE_NAME FEATURE_STRING FEATURE_DEFAULT_STRING)
if (feature STREQUAL "${FEATURE_NAME}")
string(APPEND file_content "
# if !(defined(${def_name}) && ${def_name})
# define ${FEATURE_STRING} ${FEATURE_DEFAULT_STRING}
# endif
\n")
endif()
endmacro()
function(_check_feature_lists C_FEATURE_VAR CXX_FEATURE_VAR)
foreach(feature ${ARGN})
if (feature MATCHES "^c_std_")
# ignored
elseif (feature MATCHES "^cxx_std_")
# ignored
elseif (feature MATCHES "^cxx_")
list(APPEND _langs CXX)
list(APPEND ${CXX_FEATURE_VAR} ${feature})
elseif (feature MATCHES "^c_")
list(APPEND _langs C)
list(APPEND ${C_FEATURE_VAR} ${feature})
else()
message(FATAL_ERROR "Unsupported feature ${feature}.")
endif()
endforeach()
set(${C_FEATURE_VAR} ${${C_FEATURE_VAR}} PARENT_SCOPE)
set(${CXX_FEATURE_VAR} ${${CXX_FEATURE_VAR}} PARENT_SCOPE)
set(_langs ${_langs} PARENT_SCOPE)
endfunction()
function(write_compiler_detection_header
file_keyword file_arg
prefix_keyword prefix_arg
@ -264,13 +304,13 @@ function(write_compiler_detection_header
endif()
set(options ALLOW_UNKNOWN_COMPILERS ALLOW_UNKNOWN_COMPILER_VERSIONS)
set(oneValueArgs VERSION EPILOG PROLOG OUTPUT_FILES_VAR OUTPUT_DIR)
set(multiValueArgs COMPILERS FEATURES)
set(multiValueArgs COMPILERS FEATURES BARE_FEATURES)
cmake_parse_arguments(_WCD "${options}" "${oneValueArgs}" "${multiValueArgs}" ${ARGN})
if (NOT _WCD_COMPILERS)
message(FATAL_ERROR "Invalid arguments. write_compiler_detection_header requires at least one compiler.")
endif()
if (NOT _WCD_FEATURES)
if (NOT _WCD_FEATURES AND NOT _WCD_BARE_FEATURES)
message(FATAL_ERROR "Invalid arguments. write_compiler_detection_header requires at least one feature.")
endif()
@ -377,21 +417,8 @@ function(write_compiler_detection_header
)\n")
endif()
foreach(feature ${_WCD_FEATURES})
if (feature MATCHES "^c_std_")
# ignored
elseif (feature MATCHES "^cxx_std_")
# ignored
elseif (feature MATCHES "^cxx_")
list(APPEND _langs CXX)
list(APPEND CXX_features ${feature})
elseif (feature MATCHES "^c_")
list(APPEND _langs C)
list(APPEND C_features ${feature})
else()
message(FATAL_ERROR "Unsupported feature ${feature}.")
endif()
endforeach()
_check_feature_lists(C_features CXX_features ${_WCD_FEATURES})
_check_feature_lists(C_bare_features CXX_bare_features ${_WCD_BARE_FEATURES})
list(REMOVE_DUPLICATES _langs)
if(_WCD_OUTPUT_FILES_VAR)
@ -606,6 +633,29 @@ template<> struct ${prefix_arg}StaticAssert<true>{};
endif()
endforeach()
foreach(feature ${${_lang}_bare_features})
string(TOUPPER ${feature} feature_upper)
set(feature_PP "COMPILER_${feature_upper}")
set(def_name ${prefix_arg}_${feature_PP})
_simplebaredefine(c_restrict restrict "")
_simplebaredefine(cxx_constexpr constexpr "")
_simplebaredefine(cxx_final final "")
_simplebaredefine(cxx_override override "")
if (feature STREQUAL cxx_nullptr)
set(def_value "nullptr")
string(APPEND file_content "
# if !(defined(${def_name}) && ${def_name})
# if ${prefix_arg}_COMPILER_IS_GNU
# define ${def_value} __null
# else
# define ${def_value} 0
# endif
# endif
\n")
endif()
_simplebaredefine(cxx_noexcept noexcept "")
endforeach()
string(APPEND file_content "#endif\n")
endforeach()

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@ -190,7 +190,7 @@ write_compiler_detection_header(
ALLOW_UNKNOWN_COMPILERS
)
# intentionally abuse the TEST_NULLPR variable: this will only work
# intentionally abuse the TEST_NULLPTR variable: this will only work
# with the fallback code.
check_cxx_source_compiles("#include \"${CMAKE_CURRENT_BINARY_DIR}/test_compiler_detection_allow_unknown.h\"
int main() {\n int i = TEST_NULLPTR;\n return 0; }\n"
@ -199,3 +199,16 @@ int main() {\n int i = TEST_NULLPTR;\n return 0; }\n"
if (NOT file_include_works_allow_unknown)
message(SEND_ERROR "Inclusion of ${CMAKE_CURRENT_BINARY_DIR}/test_compiler_detection_allow_unknown.h was expected to work, but did not.")
endif()
# test for BARE_FEATURES
write_compiler_detection_header(
FILE "${CMAKE_CURRENT_BINARY_DIR}/test_compiler_detection_bare_features.h"
PREFIX TEST
COMPILERS GNU Clang AppleClang MSVC SunPro Intel
VERSION 3.1
BARE_FEATURES cxx_nullptr cxx_override cxx_noexcept cxx_final
)
add_executable(WriteCompilerDetectionHeaderBareFeatures main_bare.cpp)
set_property(TARGET WriteCompilerDetectionHeaderBareFeatures PROPERTY CXX_STANDARD 11)

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@ -0,0 +1,23 @@
#include "test_compiler_detection_bare_features.h"
class base
{
public:
virtual ~base() {}
virtual void baz() = 0;
};
class foo final
{
public:
virtual ~foo() {}
char* bar;
void baz() noexcept override { bar = nullptr; }
};
int main()
{
foo f;
return 0;
}

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@ -1,5 +1,6 @@
CMake Error at .*Modules/WriteCompilerDetectionHeader.cmake:[0-9]+ \(message\):
Unsupported feature not_a_feature.
Call Stack \(most recent call first\):
.*Modules/WriteCompilerDetectionHeader.cmake:[0-9]+ \(_check_feature_lists\)
InvalidFeature.cmake:4 \(write_compiler_detection_header\)
CMakeLists.txt:3 \(include\)